satellite

Satellite

(religion, spiritualism, and occult)

A satellite is any body that orbits another body. The body being orbited is referred to as the primary. The most familiar examples of satellites are the Moon, a satellite of Earth, and Earth, a satellite of the Sun. This term was originally used to refer to attendants of important people. It was first applied to celestial bodies by Johannes Kepler, who used the term satellite to refer to the moons of Jupiter.

Satellite

in astronomy, a body of the solar system that revolves about a planet under the action of the planet’s gravitational attraction. The four brightest satellites of Jupiter—lo, Europa, Ganymede, and Callisto—were, aside from the earth’s moon, the first satellites to be observed. They were discovered by Galileo in 1610. By 1975, 33 satellites of the planets were known: one, the moon, of the earth, two of Mars, 13 of Jupiter, ten of Saturn, five of Uranus, and two of Neptune.

Satellites travel within the gravitational fields of the planets in orbits that differ only slightly in shape from ellipses. The deviations of the actual orbits from elliptical orbits are a result of perturbations caused by the sun’s attraction and by the deviation of the planets’ shapes from a spherical shape. The perturbations that satellites introduce into each other’s orbits can be used to determine the masses of the satellites. The orbital motion of most satellites is direct. In other words, the satellite revolves about the planet in the same direction that the planet revolves about the sun—that is, in a counterclockwise direction when viewed from the north pole of the ecliptic. The only satellites to have retrograde orbits are the satellites VIII, IX, XI, and XII of Jupiter, Saturn’s satellite Phoebe, Uranus’ satellites, and Neptune’s satellite Triton. Table 1 gives the principal data on the known satellites of the planets.

The satellites Phobos and Deimos of Mars are remarkable for their proximity to the planet and their rapid motion. The inner satellite, Phobos, revolves about Mars faster than Mars rotates on its axis, so that an observer on the Martian surface would see the satellite rise in the west and set in the east. Phobos rises and sets twice in a Martian day. Deimos moves across the sky more slowly: more than 2½ days pass between the time the satellite rises above the horizon and the time it sets. Both satellites move almost exactly in the equatorial plane of Mars. In 1972 the Mariner 9 space probe took close photographs of Phobos and Deimos. Both satellites proved to be irregular in shape. Phobos’ dimensions are 27 km × 21 km × 19 km, and those of Deimos are 15 km × 12 km × 11 km; the measurement error here is 0.5–3 km. The geometrical albedo of the Martian satellites does not exceed 0.05—that is, in terms of reflectivity they are comparable to the darkest parts of the lunar maria. Phobos and Deimos are covered with many craters. One crater on Phobos has a diameter of approximately 5.3 km. The craters were undoubtedly formed by impacts.

The four largest satellites of Jupiter—that is, the satellites discovered by Galileo—are comparatively bright objects of the fifth and sixth magnitude. Their orbits are almost circular, and the

Table 1. Satellites of the planets (1975 data)

Planet

Satellite

Mean distance from planet (thousands of km)

Sidereal period of revolution (days)

Eccentricity

Inclination of orbit to planet’s equatorial plane (degrees)

Diameter (km)

Mass (mass of moon = 1)

Year of discovery

Earth

Moon

384.4

27.3

0.055

23.4

3,476

1.00

–

Mars

Phobos

9.4

0.3

0.016

1.1

27

–

1877

Deimos

23.5

1.3

0.001

1.8

15

–

1877

Jupiter

V

181

0.5

0.003

0.4

220

–

1892

l lo

422

1.8

0.000

0.0

3,640

0.99

1610

I I Europa

671

3.6

0.000

0.0

3,100

0.64

1610

III Ganymede

1,070

7.2

0.001

0.0

5,270

2.11

1610

IV Callisto

1,880

16.7

0.007

0.0

5,000

1.32

1610

XIII

11,100

239

0.15

27

–

–

1974

VI

11,500

251

0.16

28

160

–

1904

VII

11,750

260

0.21

25

60

–

1905

X

11,750

260

0.13

29

18

–

1938

XII

21,000

625

0.17

147

16

–

1951

XI

22,500

700

0.21

164

22

–

1938

VIII

23,500

740

0.38

145

16

–

1908

I X

23,700

755

0.28

153

20

–

1914

Saturn

Janus

160

0.7

0.000

0.0

220

–

1966

Mimas

186

0.0

0.020

1.5

400

0.001

1789

Enceladus

238

1.4

0.004

0.0

500

0.001

1789

Tethys

295

1.9

0.000

1.1

1,000

0.009

1684

Dione

378

2.7

0.002

0.0

1,150

0.014

1684

Rhea

528

4.5

0.001

0.4

1,600

0.03

1672

Titan

1,223

15.9

0.029

0.3

5,000

1.92

1655

Hyperion

1,484

21.3

0.104

0.4

350

–

1848

lapetus

3,563

79.3

0.028

14.7

1,800

0.019

1671

Phoebe

12,950

550.4

0.163

150

300

–

1898

Uranus

Miranda

130

1.4

0.017

3.4

400

–

1948

Ariel

192

2.5

0.003

0.0

1,400

–

1851

Umbriel

267

4.1

0.004

0.0

1,000

–

1851

Titania

439

8.7

0.024

0.0

1,800

–

1787

Oberon

586

13.5

0.001

0.0

1,600

–

1787

Neptune

Triton

354

5.9

0.000

160

4,000

1.8

1846

Nereid

5,510

365.0

0.750

28

600

–

1949

planes of their orbits approximately coincide with the plane of the planet’s equator. The first determination of the speed of light was made in 1676 on the basis of observations of the eclipses of these satellites. Ganymede and Callisto are larger than the planet Mercury. For each of the four satellites, the period of rotation is the same as the period of revolution about Jupiter. Consequently, each satellite always presents the same side to the planet. A considerable part of the surfaces of Europa and Ganymede is covered with ice. The Pioneer 10 spacecraft discovered in 1973 that Io has a dense atmosphere. Jupiter’s satellite XIII was discovered in October 1974.

Saturn’s satellite Titan is larger than Mercury. Titan has an atmosphere, which, like the atmosphere of Saturn, contains methane and ammonia. The closest satellite to the planet, Janus, was discovered on Dec. 15,1966, when Saturn’s rings were invisible. This satellite is usually concealed in the halo of the brilliant rings.

The orbital planes of the satellites of Uranus are close to the equatorial plane of the planet. The satellites revolve in the same direction as Uranus rotates. Since, however, the equatorial plane of the planet is tilted at an angle of 98° to the plane of the planet’s orbit, Uranus moves with its satellites as if it were lying on its side.

Neptune’s satellite Triton was discovered in 1846, two weeks after the discovery of the planet. Triton is larger in size and greater in mass than the moon. The other satellite, Nereid, has a highly eccentric orbit. As a result, its distance from the planet varies from 1.5 to 9.6 million km.

Most of the names of the satellites were taken from ancient mythology and works of literature. The satellites of Jupiter discovered by Galileo are also designated by the Roman numerals I, II, III, and IV, in order of increasing distance from Jupiter. Jupiter’s remaining satellites, which were discovered later, are designated by Roman numerals in the chronological order of the satellites’ discovery.

G. A. CHEBOTAREV

What does it mean when you dream about a satellite?

A dream about a satellite is most likely about communication, particularly at a global level. Alternatively, a satellite is something that is trapped by the gravitational pull of another heavenly body.

That this time would be easily measured I had no doubt, since so plain were the landmarks upon the under surface of the satellite that it would be but necessary to erect a simple instrument and mark the instant of passage of a given landmark across the instrument.

The archipelago is a little world within itself, or rather a satellite attached to America, whence it has derived a few stray colonists, and has received the general character of its indigenous productions.

If I wished a boy to know something about the arts and sciences, for instance, I would not pursue the common course, which is merely to send him into the neighborhood of some professor, where anything is professed and practised but the art of life; -- to survey the world through a telescope or a microscope, and never with his natural eye; to study chemistry, and not learn how his bread is made, or mechanics, and not learn how it is earned; to discover new satellites to Neptune, and not detect the motes in his eyes, or to what vagabond he is a satellite himself; or to be devoured by the monsters that swarm all around him, while contemplating the monsters in a drop of vinegar.

Mr Inspector had not moved, and had given no order; but, the satellite slipped his back against the wicket, and laid his left arm along the top of it, and with his right hand turned the bull's-eye he had taken from his chief--in quite a casual manner--towards the stranger.

Nobody can live entirely without social intercourse; and Legree encouraged his two black satellites to a kind of coarse familiarity with him,--a familiarity, however, at any moment liable to get one or the other of them into trouble; for, on the slightest provocation, one of them always stood ready, at a nod, to be a minister of his vengeance on the other.

They have likewise discovered two lesser stars, or satellites, which revolve about Mars; whereof the innermost is distant from the centre of the primary planet exactly three of his diameters, and the outermost, five; the former revolves in the space of ten hours, and the latter in twenty-one and a half; so that the squares of their periodical times are very near in the same proportion with the cubes of their distance from the centre of Mars; which evidently shows them to be governed by the same law of gravitation that influences the other heavenly bodies.

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